Guidelines for malaria prevention in travellers from the United ...

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G UIDELINES FOR M ALARIA P REVENTION IN T RAVELLERS FROM THE U NITED K INGDOM Q9. What is the easiest way to calculate the correct dose of chloroquine for babies and young children? A. The dose steps for chloroquine syrup are not the same as for chloroquine tablets and a child may be prescribed a different dose of chloroquine depending on whether they take tablets or syrup (see tables 4 and 5, chapter 4). The main reason for any differences is due to the different amount of chloroquine base within the syrup and the tablets. The chloroquine syrup formulation contains 50 mg chloroquine base / 5 mls syrup. The amount of chloroquine base contained within the tablets is 150mg (Nivaquine) and 155mg (Avloclor). An additional factor which might be confusing is that the packet insert for chloroquine phosphate (Avloclor) gives different dosages (usually lower) for children than in these guidelines and the BNF. The ACMP guidelines and BNF dosages should be used. While there is an optimum dose of chloroquine base for children of every weight, the final dosage given to the child will depend, in part, on the practicality of administering the formulation of chloroquine available (i.e. either tablet or syrup). E.g., when dividing tablets for children, it is not possible to break a tablet into thirds, so the dosages will involve either a half or a quarter of a tablet. The tables in chapter 4 have been calculated based on weight and surface area and the most accurate dose according to the weight is recommended. Although differences occur, all recommended dosages in the tables fall within accepted limits of toxicity. It is important not to overdose children with chloroquine as severe toxicity can occur. A practical approach when calculating children's dosages for chloroquine is to decide on the most appropriate preparation (either tablet or syrup) for the child and calculate the dose appropriate to that preparation, according to the tables in chapter 4. Q10. Many travellers I see are travelling through areas where different antimalarials are recommended as they progress through their journey. How do we advise these travellers? A. Travellers planning extensive journeys across continents will often travel into areas which have different malaria chemoprophylaxis recommendations. In these situations it is important that the traveller is protected in all areas of risk and the choice of medication needs to reflect the overall risk. It may be possible to move from one regimen to another, although for shorter trips this may not be practical. For example, a traveller visiting parts of India for 2 weeks (where chloroquine plus proguanil may be recommended) and then going on to areas in Myanmar and Cambodia for 6 weeks (where mefloquine, doxycycline or atovaquone/proguanil may be recommended) would be advised to take either mefloquine, doxycycline or atovaquone/proguanil for the whole of the visit rather than 90 change from chloroquine and proguanil to one of the other agents.
G UIDELINES FOR M ALARIA P REVENTION IN T RAVELLERS FROM THE U NITED K INGDOM Q11. Which antimalarial drugs can I advise for a traveller who has epilepsy? A. Both chloroquine and mefloquine are unsuitable for those with epilepsy. For areas with a high risk of chloroquine resistant Plasmodium falciparum, doxycycline or atovaquone / proguanil can be used. However for children under the age of 12 the only suitable antimalarials under these circumstances will be atovaquone / proguanil (Malarone®) (bearing in mind the length of travel). Proguanil alone can be given for malarious areas without chloroquine resistance. Phenytoin, carbamazepine and barbiturates reduce the half life of doxycycline; in theory the dose should be increased for those taking these drugs. However, there is no evidence that this is necessary, and a dose adjustment is not recommended. Q12. What do I advise for the traveller with Glucose 6-phosphate dehydrogenase deficiency? A. Glucose 6-phosphate dehydrogenase (G6PD) is an enzyme in the hexose monophosphate shunt of the glycolytic pathway. This shunt supports the red cell’s protection against oxidative damage. Absence of G6PD renders the red cell liable to haemolysis in the presence of some drugs. The most common G6PD deficiency allele in Africa (G6PD A-) has been shown to confer some resistance to malaria in both hemizygous males and heterozygous females 61 . Nevertheless, all G6PD-deficient travellers to malarious areas still require appropriate chemoprophylaxis. Chloroquine There is a theoretical risk of haemolysis in some G6PD-deficient individuals who receive chloroquine. This risk is acceptable in acute malaria 59 and G6PD levels are not usually checked before using chloroquine in treatment doses. Haemolysis does not appear to be a problem when chloroquine is given in the dose recommended for malaria chemoprophylaxis so there is no need to withhold chloroquine prophylaxis from those known to be G6PD-deficient. Primaquine This drug is not currently recommended as a first line agent for malaria prevention in UK travellers, but may be considered in special circumstances on expert advice 27 . There is a definite risk of haemolysis in G6PD-deficient individuals. The traveller’s G6PD level must be checked before primaquine is prescribed and G6PD deficiency contraindicates its use for prophylaxis. 91
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Guidelines for Malaria Prevention i
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ABBREVIATIONS G UIDELINES FOR M ALA
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G UIDELINES FOR M ALARIA P REVENTIO
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2. Awareness of Risk 2.1 What is ma
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2.3 The malarial illness Malaria ca
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ut the risk of contracting malaria
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G UIDANCE UIDELINESFROM FOR THE M A
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Page 63 and 64: 5. Diagnosis Suspected malaria is a
Page 69 and 70: individuals' medical history should
Page 71 and 72: 6.9 Liver disease Most antimalarial
Page 73 and 74: 7 - Special Categories 7.1 Children
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Page 77 and 78: As examples, cruises in the Caribbe
Page 79 and 80: 7.10 Students and children at board
Page 81 and 82: FIGURE 8 Efficacy of regimens It is
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Page 85 and 86: 8.1 What malaria prevention should
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Page 97 and 98: 9. Information Resources 9.1 Expert
Page 99 and 100: 9.4 References 1 General Medical Co
Page 101 and 102: 29 Hill DR. Travel Associated Disea
Page 103 and 104: 56 Steketee RW, Wirima JJ, Slutsker
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